Structural connection between rotatable parts



Oct 1963 H. o. SCHERENBERG 3,108,649

STRUCTURAL CONNECTION BETWEEN ROTATABLE PARTS Filed April 16, 1962ATTORNEYS.

United States Patent 5,108,640 STRUCTURAL CflNNEtlTIQN BETWEEN ROTATABLEPARTS Hans Q. Scherenberg, Stuttgart-Heumaden, Germany, as-

srgnor to Daimler-Benz Alttiengesellschaft, Stuttgart- Unterturldleirn,Germany Filed Apr. 16, 1962, Ser. Na. 187,476 Clauns priority,application Germany Apr. 18, 1951 4 Claims. (Cl. 17ll35.4)

The present invention relates to helicopter blade or propellerarrangement, and more particularly to the connection between a jetpropulsion unit, especially of a ram jet unit, and the 'end of apropeller blade, especially in helicopters.

It is known to drive the propeller of helicopters by means of ram jetunits arranged at the end of the blade. This kind of propulsion unit isparticularly suited therefor because ram jet units operate economicallyat the high velocities which occur at the ends of the blade. On theother hand, large centrifugal forces occur with high peripheralvelocities to which the fastening and mounting element; of the jet unitand the propeller blades are subecte The present invention aims atproviding a connection between the end of the blade and the propulsionunit and a suspension of the latter in the radial direction, whichconnection is capable to favorably absorb the high stresses and loadsoccurring during operation and, in particular, to relieve the propellerblade far-reachingly insofar as sturdiness, rigidity and strength ofmaterials thereof are concerned.

The present invention proposes as solution to this purpose to clamp thehousing of the jet propulsion unit or of the base thereof against theend of the blade by means of a rope, cable, chain, tie rod, or the likeclamping member which extends in the direction of the longitudinal axisof the propeller blade.

With a length of the cable extending over the entire radial extent ofthe propeller blade and with a fastening or securing of the cable to therotor shaft or within the blade root, the propeller blade may be made inits entirety from a simple and light structural material, such assynthetic resin, since the cross section of the blade-in addition toother loads and stresses-4s no longer subjected principally totractional forces or tensile stresses as was the case heretofore;instead the tractional forces are absorbed exclusively by the cablewhich may, additionally be installed under an initial or pre-stress. Thecable system occupies very little space within the propeller blade orwithin the hollow blade girder so that sufficient room is left for theaccommodation of the fuel supply lines and of the electric wiring.

A rectilinear guide arrangement in accordance with the present inventionwhich is provided between the propulr sion unit housing or the base ofthe propulsion unit, on the one hand, and the end of the propellerblade, on the other, assures also with a greater lengthening or stretcing of the cable as compared to the considerably smaller lengthening ofthe propeller blade, that during operation the center of gravity of thepropulsion unit will continue to remain on the longitudinal axis of thepropeller blade and that constant angular position of the longitudinalaxis of the propulsion unit is maintained with respect to theaforementioned longitudinal axis, in order to obtain load conditions forthe propeller blade which are as favorable as possible and optimum airinlet conditions for the propulsion drive unit. Furthermore, therectilinear guide arrangement between the base of the propulsion unitand the end of the blade absorbs the circumferential forces andtransmits the same to the propeller blade.

Accordingly, it is an object of the present invention to "Ice provide aconnection between the blades of a helicopter and a propulsion driveunit mounted at the outer end thereof which obviates the aforementionedshortcomings and inadequacies encountered in the prior art devices.

It is another object of the present invention to provide a connectionbetween the propulsion drive unit especially ram jet and the out end ofa helicopter blade which is capable of withstanding the forces thatoccur as a result of the high velocities occurring thereat and yetrelieves the blade of tensional stresses caused by centrifugal forcesacting on the drive unit.

Still another object of the present invention resides in the provisionof a clamping arrangement for clamping a jet drive unit against theouter end of a helicopter propeller blade which makes possible the useof relatively simple material for the blade construction and leavesadequate space on the inside of the blade for the accommodation of thefuel lines, Wirings, etc., therein.

Another object of the present invention resides in the provision of aconnection between a propulsion drive unit and the outer end of apropeller blade which, notwithstanding its removal of tensional stresseswithin the propeller blade, assures the maintenance of proper positionof the drive unit at the outer end of the blade.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, two embodiments in accordance with thepresent invention, and wherein FEGURE 1 is a plan view, with partsbroken away, of a propeller blade provided with a double cable system inaccordance with the present invention, and

FIGURE 2 is a plan view, also with parts broken away, of a propellerblade with a single cable system in accordance with the presentinvention.

Referring now to the drawing wherein like reference numerals are usedthroughout the various views to designate like parts, a ram jet unitgenerally designated by reference character T is arranged at the outerend of the propeller blade generally designated by reference character Bwhich rotates around the shaft 11 thereof. A base member 12 is securedto the base of the drive unit generally designated by referencecharacter F and is provided with recesses or apertures 13 extending inthe direction of the longitudinal axis of the propeller blade B, whilecorrespondingly shaped ledge members or bolts 15, which are disposed ona head piece 14 inserted into the outer end of the blade, are guidedwithin these apertures 13.

According to FIGURE 1, a roller 16 is supported within the base member12 about which is slung an endless cable 8, which on the other hand, issuspended in an adjustable tensioning or stretching device disposed inthe blade root 21 which is displaceably provided in the longitudinaldirection. The tensioning device consists of the element 17 for thesuspension of the cable S and is provided with guide strips or ledgeportions 17' which are guided within guide grooves 18 disposed withinthe blade root 21. A thread is provided within element 17 into whichengages a threaded bolt 19 with the aid of which the cable S istensioned, whereby the bolt 19 is supported against the blade root 21.

According to FIGURE 2, only a single cable system S is provided to thetwo ends of which are secured conical end pieces 2A) which are suspendedin corresponding apertures provided within the base member 12 and withinpart 17 of the tensioning device. The end pieces 20 may additionally beprovided with a profiled shape along the outer circumference thereof inorder to increase the form-locking engagement thereof with the partsreceiving the same which may be provided with complementaryconfigurations along the internal contours thereof.

While I have shown and described only two embodiments in accordance Withthe present invention, it is understood that the same is not limitedthereto, but is susceptible of many changes and modifications within thespirit and scope thereof as known to a person skilled in the art, and Itherefore do not Wish to be limited to the details shown and describedherein, but intend to cover all such changes and modifications as areencompassed by the scope of the appended claims.

l claim:

1. In a propeller blade assembly for a helicopter-like vehicle having apropulsion drive unit including a base portion and a propeller blademeans, said blade means having an inner end and an outer end withrespect to said vehicle and said propulsion drive unit base portionbeing secured to the outer end of said blade means, the improvementessentially consisting of an improved connecting means for connectingsaid propulsion drive unit to said outer end of the blade means and forsuspending said propulsion drive unit radially to absorb the highstresses and loads on the connecting means occurring during operation ofthe propulsion drive unit, said connecting means comprising means forclamping the base portion of said drive unit against the outer end ofsaid blade means under compression to absorb the centrifugal forces ofthe drive unit and blade means including cable means extendingsubstantially in the longitudinal direction of and over the entirelength of said blade means and on the inside thereof, adjustabletensioning means adjustingly connecting said cable means with the rootof said blade means, and rectilinear guide means between said baseportion and said outer end of the blade means including a base memberprovided on said propulsion drive unit and having aperture meansextending substantially in the longitudinal direction of said blademeans, and a head piece disposed in the outer end of said blade means,said head piece having complementary pin means thereon guided withinsaid aperture means in the assembled condition of said connecting means,said cable means being secured to said base member.

2. In a propeller blade assembly for a helicopter-like vehicle having apropulsion drive unit including a base portion and a propeller blademeans, said blade means having an inner end and an outer end withrespect to said vehicle and said propulsion drive unit base portionbeing secured to the outer end of said blade means,

the improvement essentially consisting of an improved connecting meansfor connecting said propulsion drive unit to said outer end of the blademeans and for suspending said propulsion drive unit radially to absorbthe high stresses and loads on the connecting means occurring duringoperation of the propulsion drive unit,

said connecting means comprising means for clamping the base portion ofsaid drive unit against the outer end of said blade means undercompression to absorb the centrifugal forces of the drive unit and blademeans including cable means extending substantially in the longitudinaldirection or" and over the entire length of said blade means and on theinside thereof,

adjustable tensioning means adjustingly connecting said cable means withthe root of said blade means including an element for suspending saidcablc means, the root of said blade means being provided with guidegrooves therein, said element having guide strips guided Within saidguide grooves, said cable means being secured to said element, and boltmeans threadably connected to said element and supported against theroot of said blade means for adjusting the tension of said cable means,and

rectilinear guide means between said base portion and said outer end ofthe blade means including a base member provided on said propulsiondrive unit and having aperture means extending substantially in thelongitudinal direction of said blade means, and a head piece disposed inthe outer end of said blade means, said head piece having complementarypin means th reon guided within said aperture means in the assembledcondition of said connecting means, said cable means being secured tosaid base member.

3. An assembly as defined in claim 2, wherein said cable means is anendless cable secured to said base member by a roller attached thereto.

4. An assembly as defined in claim 2, wherein said cable means is asingle cable system having tapered cnd pieces secured thereto and seatedin complementary apertures provided in said base member and saidelement.

References Cited in the file of this patent UNITED STATES PATENTS2,421,699 Johnson June 3, 1947 2,547,226 Michael Apr. 3, 1951 2,557,220Gazda June 19, 1951 2,665,862 Grill Jan. 12, 1954 2,701,021 Sargent Feb.1, 1955 FOREIGN PATENTS 753,545 Great Britain July 25, 1956

1. IN A PROPELLER BLADE ASSEMBLY FOR A HELICOPTER-LIKE VEHICLE HAVING APROPULSION DRIVE UNIT INCLUDING A BASE PORTION AND A PROPELLER BLADEMEANS, SAID BLADE MEANS HAVING AN INNER AND AN OUTER END WITH RESPECT TOSAID VEHICLE AND SAID PROPULSION DRIVE UNIT BASE PORTION BEING SECUREDON THE OUTER END OF SAID BLADE MEAND, THE IMPROVEMENT ESSENTIALLYCONSISTING OF AN IMPROVED CONNECTING MEANS FOR CONNECTING SAIDPROPULSION DRIVE UNIT TO SAID OUTER END OF THE BLADE MEANS AND FORSUSPENDING SAID PROPULSION DRIVE UNIT RADIALLY TO ABSORB THE HIGHSTRESSES AND LOADS ON THE CONNECTING MEANS OCCURING DURING OPERATION OFTHE PROPULSION DRIVE UNIT, SAID CONNECTING MEANS COMPRISING MEANS FORCLAMPING THE BASE PORTION OF SAID DRIVE UNIT AGAINST THE OUTER END OFSAID BLADE MEANS UNDER COMPRESSION TO ABSORB THE CENTRIFUGAL FORCES OFTHE DRIVE UNIT AND BLADE MEANS INCLUDING CABLE MEANS EXTENDINGSUBSTANTIALLY IN THE LONGITUDINAL DIRECTION OF AND OVER THE ENTIRELENGTH OF SAID BLADE MEANS AND ON THE INSIDE THEREOF, ADJUSTABLETENSIONING MEAND ADJUSTINGLY CONNECTING SAID CABLE MEANS WITH THE ROOTOF SAID BLADE MEANS, AND RECTILINERR GUIDE MEANS BETWEEN SAID BASEPORTION AND SAID OUTER END OF THE BLADE MEANS INCLUDING A BASE MEMBERPROVIDED ON SAID PROPULSION DRIVE UNIT AND HAVING APERTURE MEANSEXTENDING SUBSTANTIALLY IN THE LONGITUDINAL DIRECTION OF SAID BLADEMEANS, AND A HEAD PIECE DISPOSED IN THE OUTER END OF SAID BLADE MEANS,SAID HEAD PIECE HAVING COMPLEMENTARY PIN MEANS THEREON GUIDED WITHINSAID APERTURE MEANS IN THE ASSEMBLED CONDITION OF SAID CONNECTING MEANS,SAID CABLE MEANS BEING SECURED TO SAID BASE MEMBER.